provides assistance to health care providers working
ipsilateral and contralateral (indicated by failure
with migrant and seasonal farm workers. MCN, the
second-largest clinical network in the nation, brings
tests, analysis by gestational TCE exposure,
together clinicians from various professions to meet
and analysis using three exposure categories
the needs of migrant and seasonal farm workers.
weakened the hypothesis that all of these
Seven MCN member clinics throughout South Caro-
lina provide support to migrant workers and their
were caused by TCE exposure. The absence of an
families.
exposure.
Health Studies
When grouped by age, no differences in OSH
Health studies are investigations conducted to deter-
function were found between the exposed and
mine the relationships between exposures to hazard-
control groups. When children exposed during
ous substances and adverse health effects. They also
gestation were compared with children exposed
define health problems that require further investiga-
later in life, no differences in oral motor, speech,
tion through, for example, health surveillance or an
and hearing test results were detected.
epidemiologic study. Following is an example of a
health study that ATSDR conducted or supported in
Resource Materials
the state of South Carolina.
ATSDR develops materials that public health profes-
Impact of Trichloroethylene (TCE) Exposure
sionals and medical care providers can use to assess
on Oral Motor, Speech, and Hearing in
the public health impacts of chemical exposures.
Children--In 1989, ATSDR began enrolling
Resources are available in print, on the ATSDR Web
eligible individuals in the TCE Subregistry of the
site, and on CD-ROM. For example, medical man-
National Exposure Registry. Four thousand forty-
agement guidelines are available for acute chemi-
one living individuals--including 357 children
cal exposures to more than 40 chemicals. ATSDR's
who were 10 years of age or younger--were
toxicological profiles comprehensively describe
enrolled. Analyses of the health information at
health effects; pathways of human exposure; and the
the baseline data collection indicated an excess
behavior of more than 250 hazardous substances in
of hearing impairments and speech impairments
air, soil, and water at hazardous waste sites. In the
in this particular age group. Given the known
last 5 years, more than 15,200 of these profiles have
and suspected effects of TCE on cranial nerves,
been sent to requesters, including representatives of
it was felt that additional information was
federal, state, and local health and environmental
needed to adequately address the excesses of
departments; academic institutions; private indus-
speech and hearing disorders. The University
tries; and nonprofit organizations in South Carolina.
ATSDR has also developed extensive resources for
agreement with ATSDR, examined the impact
community members.
of low-level, long-term TCE exposure on oral
motor, speech, and hearing (OSH) status in
children less than 14 years of age. To identify
OSH status, screening and in-depth assessments
were conducted on TCE-exposed children from
the TCE Subregistry, and on a nonexposed,
age-matched control group, using the baseline
information from the TCE Subregistry.
The study found that exposed children had
significantly higher rates of abnormal dentition,
high palatal arch, abnormal outer cochlear hair
For more information, contact ATSDR toll-free
cell function in the left ear only (indicated by
at 1-888-42ATSDR (1-888-422-8737) or visit the
failure of otoacoustic emission screening),
ATSDR Web page at www.atsdr.cdc.gov.
September 2003
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